And yet you've probably never seen my tweets, because I'm generally not replying to celebs' tweets. Bots (owners) are trying harder than most people to maximise their visibility before getting banned, so it's expected that you would notice a higher proportion than they actually represent. That's not to say I have any reason to think the bot share isn't higher, just I don't think it's possible for any single person to judge anywhere near accurately considering the huge scale of Twitter and that therefore any one of us users is only seeing a tiny, tiny fraction of the accounts/tweets being posted.